Data Structures: Hash Tables


Learn the basics of Hash Tables, one of the most useful data structures for solving interview questions. This video is a part of HackerRank’s Cracking The Coding Interview Tutorial with Gayle Laakmann McDowell.



  1. Rocket speed of explanation. You should concentrate more on the concepts and talk a bit slower.. you rush like a rocket, seriously. Explain and iterate over the concepts more, bring some real life analogies and so on.

  2. These videos are far too complex than they need to be, atleast for me. I think it's not for beginners. Rather, it's for someone who knows this stuff, and is just looking for some revision.

  3. The class hashtable starts like this :
    Class Hashtable{
    LinkedList[] data
    The variable data should be an arrayList in order to have the complexity of O(1) when getting one element . Am I missing something?

  4. Yeah, I don't intend this to be negative. However, I think your strategy to break down Hash Tables is too messy. I would refrain from adding unnecessary clutter on your video (Left Column) and simply just talk about it. This would probably help out the most when trying to break down a complex Data Structure into something more easily understandable!
    No offense! We are all here trying to learn. Thanks for posting!

  5. Hash tables are amazingly fast. My new favorite data structure. The only downside is they take up a lot of space when they get large

  6. People complaining that they don't understand what she is explaining, you guys need to first do your own research on what a hashtable is. This video is not supposed to teach you how to build one, but it explains what a hash table is and how it works behind the scene. And I am quite confident that she has done a very good job of explaining it. One tip of advice: Do your own research first before watching a tutorial on it. This way, you will be able to fill in the gaps that you had while researching.


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